India is the world’s sixth largest energy consumer, consuming about 3 per cent of the world’s total energy per year. With a population of over one billion people living in an area of just under 3 million km², it is the second most populous country in the world, behind only China. Organisations such as DESI Power in India are advocating the decentralisation of power supply and the switch to renewable, locally available energy sources. The Malavalli biomass power plant in rural Karnataka, for example, has helped resolve local problems of electricity supply, while making use of locally available resources in a more environmentally sound way than burning coal, which is also produced locally. The plant benefits the local community, local agriculture and local industry.
Energy in India
India’s population is growing at a rate of about 1.6 per cent per year, and is expected to reach 1.16 billion by the year 2010. This population growth, coupled with continued economic growth, is driving energy demand to levels above the country’s production capacity. Overall, India’s need for power is growing at a remarkable rate. Annual electricity generation and consumption have nearly doubled since 1990. Electricity generation has grown from 275.5 billion kilowatt-hours (kWh) to 547.2 kWh, while consumption has grown from 257.1 kWh to 510.1 kWh. The country’s projected increase in electricity consumption, of between 2.6 per cent and 4.5 per cent up to 2020, is the highest for any major country.
In the face of growing demand, India’s electricity sector faces problems of capacity, poor reliability, and frequent blackouts. The anticipated electricity shortage is estimated at between 11 and 18 per cent. Currently 79 per cent of electricity comes from fossil fuels, mostly coal. India is the third largest coal-consuming country in the world, behind China and the United States; it accounts for about 8 per cent of the world’s annual coal consumption and about 7.5 per cent of the world’s annual coal production. Nearly three-quarters of India’s electricity and two-thirds of its commercial energy comes from coal, and the demand for coal has been steadily increasing over the past decade.
Not only is coal a finite resource, its burning for energy purposes is harmful to the environment. India accounts for a significant proportion (about 4.2 per cent) of the world’s total fossil-fuel-related carbon dioxide emissions. Since 1990, India’s carbon emissions have increased by over 60 per cent, and they are about nine times higher than they were in 1960. Much of this increase is due to India’s growing use of coal for power generation.
India also faces major problems with infrastructure and capacity for electricity supply, with the country’s State Electricity Boards (SEBs) ill-equipped to fund or carry out plant construction or upgrading. According to the Indian government, most SEBs are bankrupt with their cumulative transmission losses equating to about 260 billion rupees per year (US$6 billion). Much of this is due to power theft (often referred to as ‘non-technical losses’) and a pricing structure that heavily subsidises agriculture. Of all the electricity generated in India, only about 55 per cent is even billed and slightly more than 40 per cent is regularly paid for.
The failure of the central grid system of electrification has the knock-on effect of insufficiently providing for the electrical needs of the marginal groups of Indian society. Of the half a million or so villages in India, about 80,000 remain completely un-electrified. In practice, most of the so-called electrified villages do not have reliable, regular, adequate, or good quality power. This prevents commercial investment into micro-enterprises by either individuals or companies without the installation of diesel generators with very high generating costs.
To resolve India’s problem of electricity supply, local renewable sources of energy are becoming a more attractive alternative. With the advent of mature renewable energy technologies, the supply of power to remote rural areas from the centralised grid is becoming less competitive, as well as being more harmful to the environment and requiring more extensive infrastructure. Renewable options, such as electricity derived from modern, decentralised biomass gasification plants, are also being backed by projects such as the World Bank’s Asia sustainable and alternative energy programme (ASTAE).
Asia Sustainable and Alternative Energy Programme
The World Bank, along with key bilateral donors, established the Asia sustainable and alternative energy programme (ASTAE) in January 1992, as a follow up to Project FINESSE (Financing Energy Services for Small-scale Energy Users). ASTAE’s aim is to mainstream renewable and alternative energy with priority emphasis on the Asia region. To support this goal, ASTAE works with both Bank staff and client country decision-makers to incorporate alternative energy options into the design of energy sector strategies and lending operations for all of the Bank’s client countries in Asia.
ASTAE provides assistance in the identification and preparation of renewable energy and energy efficiency projects. ASTAE’s strategy also covers technical assistance to improve local technical expertise, system performance and institutional capability to design and implement alternative energy options. These activities have included:
- Training modules in energy efficiency and renewable energy options;
- Formulation of alternative energy policies;
- Design and implementation of pilot innovative delivery mechanisms;
- Technical support to improve the performance and availability of alternative energy systems; and
- Strengthening of institutional capacities.
In addition, ASTAE collaborates with numerous donor agencies and has mobilised funding for critical technical assistance in support of its work programme.
The ASTAE project supports the work of organisations such as DESI Power (Decentralised Energy Systems India). DESI Power’s programme ultimately envisages the use of renewable energy that is most suitable for a given location. In many cases the optimum solution usually turns out to be a hybrid system, with multiple energy sources required to take care of the variations in the availability of renewable energy sources. According to DESI Power, the following renewable energy technologies (RETs) are now mature and commercially available for installation and operation in rural areas in India (in alphabetical order):
- Biomass charcoal production
- Biomass combustion
- Biomass gasification
- Energy plantations and agro-forestry
- Solar photovoltaic
- Solar thermal
- Wind generators
What is biomass?
Biomass is the term used to describe all the organic matter produced by photosynthesis that exists on the Earth’s surface. The source of all energy in biomass is the sun, the biomass acting as a kind of chemical energy store. Biomass is constantly undergoing a complex series of physical and chemical transformations and being regenerated while giving off energy in the form of heat to the atmosphere. To make use of biomass for our own energy needs we can simply tap into this energy source. For many, this is in the simplest form of an open fire used to provide heat for cooking, warming water or warming the air in our home. More sophisticated technologies also exist for extracting this energy and converting it into useful heat or power in an efficient way, as adopted by Malavalli biomass plant in rural Karnataka.
Traditionally the extraction of energy from biomass is split into three distinct categories: solid biomass, liquid biofuels, and biogas. Solid biomass makes use of trees, crop residues, animal and human waste, and household or industrial residues for direct combustion to provide heat. Often the solid biomass will undergo physical processing such as cutting, chipping, or briquetting before it is burned, but it retains its solid form.
Malavalli Power Plant
A project backed by DESI Power is the now-established Malavalli biomass power plant, situated at Kirugaval Hobli, in the Mandya District of rural Karnataka. The plant has pioneered the commercial use of low-density crop residues, such as sugar cane by-products, coconut fronds, and rice/wheat straw, which are otherwise burned in the fields and cause environmental pollution. The use of crop residues as commercial fuels has previously been inhibited by low productivity and high costs associated with the collection, loading, compaction, transportation and storage of the biomass. The Malavalli plant has devised techniques by which these tasks can be performed by rural entrepreneurs with acceptable productivity and cost levels. This initiative is coupled with the production and distribution of organic fertiliser (comprising ash, agri-waste and bio fertilisers), thereby contributing to soil preservation and the mitigation of environmental pollution.
It is estimated that, for the whole of India, the generation of low-density crop residues is in excess of 100 million tonnes per annum; sugar cane waste alone constitutes more than 25 million tonnes per annum. The plant is specifically designed for the multiple firing of a wide range of these biomass products:
- Crop residues: sugar cane by-products, coconut fronds, grain straw, and the stalks and toppings of eucalyptus and casuarina.
- Mill residues: rice/peanut (groundnut)/coffee husk, bagasse, sawdust/ wood chips (e.g. sawmill waste) etc.
The firing of biomass poses challenges for combustion effectiveness and efficiency. The Malavalli plant has already acquired, and is continuing to build, knowledge assets in the surrounding area, which help in improving designs of fuel preparation systems and biomass boilers, as well as appropriate operation and management procedures in the plant.
The design of the plant also provides a 5000 megawatt capacity for households and industries in the local area, such as sugar mills, paper mills, and food processing units. This capacity is made possible through the plant’s model of decentralised power generation and distribution in rural load centres that use local resources. The Malavalli plant has pioneered a power evacuation scheme, which facilitates the use of the decentralised power-generating unit when the main electricity grid is not available. Such decentralised schemes not only reduce investment and losses in transmission, but also make rural energy distributors more socially accountable.
The Malavalli plant has a key objective of rural development through entrepreneurial efforts. Towards this goal, the plant has created skills and transactions procedures related to:
- Crop residues supply chain;
- Organic fertiliser production/distribution;
- Biomass power plant operations and maintenance;
- Rural electricity distribution.
How it Works
Biomass fuel supply chain
The biomass supply in Malavalli is managed by a local organisation, Grameena Abhivrudhi Mandali (GAM). The fuel supply operation includes the collection and loading of sugar cane waste and coconut fonds onto lorries. Typically, a group of ten members, supervised by a leader, is able to collect a combined total of about 6 tonnes of sugar cane waste and coconut fronds per day. The activities at the plant include transferring the sugar cane waste and coconut fronds from the lorries to the conveyor charge pit.
Biomass fuel supply arrangements
Fuel: Primary fuel: sugar cane waste; the leafy portion of coconut fronds (mattale).
Secondary fuel: the woody portion of coconut fronds; sawmill waste; rice, coffee and peanut husks; coconut shells.
Back-up fuel: plantation wood trimmings, such as eucalyptus and casuarinas.
Annual supplies: Primary fuel: 36,000 tonnes (with less than 25 per cent moisture content).
Secondary fuel: 7,200 tonnes (with less than 20 per cent moisture content).
Back-up fuel: 10,000 tonnes (with less than 42 per cent moisture content).
Biomass fuel processing
The primary fuel is moved by belt conveyors and processed by rotary cutters. The processed secondary and back-up fuels are transported by belt conveyors to the intermediate storage hoppers and fed to the furnace by screw conveyors. About 80 per cent of the primary fuel and 20 per cent of the secondary fuel are fed to the boiler. Back-up fuel is used whenever there is a shortage of primary fuel. The average fuel requirement is about 140 tonnes per day. The boiler is usually lit using wood chips and husk, and the fire is then maintained with the mixture of primary and secondary fuel.
Power plant technology
The technology of the biomass power plant is based on the Rankine Cycle. The main components of the plant are:
- Boiler and auxiliaries
- Steam turbine and auxiliaries
- Generator and auxiliaries
- Condenser and auxiliaries
- De-mineralisation plant
- Ash handling plant
- Effluent treatment plant
- Power evacuation facility.
The Rankine Cycle
The Rankine cycle is a thermodynamic cycle used to generate electricity in many power stations. Super-heated steam is generated in a boiler, and then expanded in a steam turbine. The turbine drives a generator, to convert the work into electricity. The remaining steam is then condensed and recycled as feed-water to the boiler. A disadvantage of using the water-steam mixture is that turbine blades can begin to corrode due to their repeated exposure to the steam.
Organic substances, which can be used below a temperature of 400ºC, do not need superheating, resulting in a higher efficiency of the cycle. This is called an Organic Rankine Cycle (ORC). An ORC can make use of low temperature waste heat to generate electricity. At these low temperatures a steam cycle would be inefficient, due to enormous volumes of low-pressure steam, causing very voluminous and costly plants. ORCs can be applied to low temperature waste heat recovery (industry), efficiency improvement in power stations, and the recovery of geothermal and solar heat.
The boiler generates steam at 445ºC, which arrives at the inlet to the steam turbine at a temperature of 440ºC. The steam turbine for the power plant has a power rating of 4500 kilowatts (kW). The auxiliary system consists of the condenser, circulating water system, demineralisation plant, potable and service water system, fire protection system, stack, and other related facilities.
A key component of the plant is the treatment of biomass ash, of which about 8 tonnes are generated per day. At the Malavalli plant, they recognise the need for 100 per cent use of biomass ash, from both a pollution perspective and in terms of agriculture, soil preservation and nutrition. At Heggur, just 1 kilometre from the plant, an ash utilisation plant has been set up. The ash is converted into organic fertiliser through a composting procedure, involving the mixing of ash with pressed mud, along with cowdung slurry containing azeotropic bacteria. The resulting bio-organic fertiliser is packaged in 50 kg bags and stacked for supply. About 100 kg of fertiliser is given free to local farmers in exchange for biomass fuel supplies to the power plant.
There are three broad benefits associated with a decentralised biomass power plant:
- It addressing the failures of centralised electricity supply.
- It is environmentally sound.
- There are spin-off benefits for local farmers, industry and the broader community.
As the above demonstrates, decentralised biomass power plants address some of the major issues faced by the Indian electricity sector. The use of biomass reduces the growing dependence on coal, which also has more harmful effects for the environment. Moreover, the processing of biomass ash into fertiliser has direct benefits for the environment and local agriculture. The decentralised nature, meanwhile, reduces the problem of illegal tapping of electricity faced by India’s SEBs. This creates a more reliable source of electricity, which benefits both the SEBs are local consumers.
‘Voltage used to be a problem. There used to be power losses and we used to get power for only six hours. We had to use the generator, which cost double the money. It wasn’t working out. Now since we got the new power we are at peace. I had one rice mill before. Since getting a better power facility, I’ve got three mills. People are getting jobs.’
Rice Mill Owner
‘Before we used to spend 12-15 Rupees travelling to pay the bill, and it used to take a whole day. Now my husband bikes to pay the bill and is home within an hour.’
Kessissoglou, N. and Spencer, L. (1998). “Rankine cycle”. Applied Thermodynamics 200. The University of Western Australia: Department of Mechanical & Materials Engineering.
Malavalli Power Plant Limited. Operating 4.5 MW Biomass Power Plant. Unpublished Plant Guidelines: Malavalli Power Plant.
Decentralised Energy Systems India (DESI Power) www.desipower.com
Energy Services Delivery Project
Global Environment Facility (GEF) www.thegef.org
World Bank: ASTAE www.astae.net/content/asia-sustainable-and-alternative-energy-program
Malavalli Biomass Plant malavalli-biomass.blogspot.co.uk
Donor and Supporting Organisations
Department for International Development (DFID) www.dfid.gov.uk
World Bank www.worldbank.org
ITDG Technical Briefs answers.practicalaction.org
Related Hands On case studies
Rice Under Fire – Bangladesh;